While other formal choices are possible, probability theory stands alone as a particularly convenient representation of the rules for manipulating degrees of plausibility. Once one obtains the standard sum and product rules, there is no impediment to obtaining all the standard results of probability theory — the central limit theorem, marginalization, etc.There are many good books on probability theory. This author has gained much insight from the book by Caticha [1]} and the book by Jaynes [2]}.
